Variation of anti-A and anti-B titers in group O potential blood donors: A pilot study.

BACKGROUND: Resuscitation with fresh whole blood is vital to preserving life on the battlefield. Transfusing low titer O whole blood (LTOWB), defined as anti-A and anti-B titer levels of <1:256, is safe because LTOWB alleviates the risk for hemolytic transfusion reactions. Because of possible variations in titer levels over time, a study was needed using US Navy and Marine Corps personnel to assess how these titers change across two assessments. METHODS: Retrospective data from group O marines and sailors (M = 25 years of age; range, 19-35 years) stationed in the San Diego region were acquired from the Armed Services Blood Program and the Composite Health Care System. Of 972 group O donors between January 2016 and November 2019, 55 donors with 2 samples were identified (N = 55). Analysis included contrasting rates of high (≥1:256) and low (<1:256) anti-A and anti-B titers on the initial and second blood tests, along with the time between testings. RESULTS: The average time between testing was 332 days (range, 35-1,121 days), which far exceeded the recommended 90-day interval (p < 0.00001). Only 45% met the 90-day recommendation. Titer status changed frequently, from low to high (anti-A, 18%; anti-B, 13%; LTOWB to not LTOWB, 21%) or from high to low (anti-A, 62%; anti-B, 78%; not LTOWB to LTOWB, 62%). CONCLUSIONS: Anti-A and anti-B titers change frequently enough to warrant testing immediately before deployment and even during deployment. The observed time elapsed between testing is unacceptably long. The present pilot study provides a foundation for a larger formal study to more fully characterize titer changes over repeated testing. LEVEL OF EVIDENCE: Diagnostic test, level IV.